Valve for rock drills



Oct. 2, 1934. 5 w HULSHIZER 1,975,229

VALVE FOR ROCK DRILLS Filed Nov. 25, 1935 BY i J I HISATTORNEY,

i atented Oct. 2:, i934- "WED STATES PAT T VALVE FOR ROCK DRILLS Application November 23, 1933, Serial No. 699,315

8 Claims.

This invention relates to rock drills, and more particularly to a distributing valve for rock drills of the fluid actuated type.

V The objects of the invention are to obtain a quick and positive action of the valve and, therefore, a rapid reciprocatory movement of the percusslve element of the drill, and to enable the percussive element to deliver blows of a character best suited to the requirements of the work.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawings illustrating the invention and in which similar reference numerals refer to similar parts,

Figure 1 is an elevation, in section, of a rock drill equipped with a valve constructed in accordance with the practice of the invention and showing the valve in position tosupply pressure fluid behind the piston for driving it on its work.- ing stroke,

Figure 2 is a view similar to Figure 1 showing the valve in the other limiting position, and

Figures 3 and 4 are views similar to Figures 7 1 and 2 of a modified form of the invention showing the valve in its limiting positions.

Referring to the drawings and at first more particularly to the form of the invention illustrated in Figures 1 and 2, 20 designates, in general, a rock drill comprising a cylinder 21 having a piston chamber 22 wherein is arranged a reciprocatory hammer piston 23. The piston 23, which controls a free exhaust port 24 in the cylinder, has a stem 25 which extends slidably through a front cylinder washer 26 serving as a closure for the front end of the piston chamber 22. A front head 27 into which'a working implement (not shown) may extend to receive the blows of the hammer piston 23 is seated against the front cylinder washer 26.

In the rear end of the cylinder 20 is an enlarged bore 28 to accommodate rotation mechanism and valve mechanism 29 and 30, respectively. The valve mechanism which is seated in the bottom of the bore 28 forms a bounding surface for the piston chamber 22 and serves as a 23 to describe a partial rotary movement for changing the position of the working implement with respect to the work.

The ratchet ring 31 serves as a seat for a back head 36 which constitutes the extreme rear casing part of the rock drill and may be securely fastened to the cylinder 21 by the usual side bolts (not shown) but which may also serve to clamp the front head 27 in assembled position.

As an additional function the back head 36 may serve as a casing for a throttle valve 37 whereby the admission of pressure fluid into the rock drill 25 is controlled. The throttle valve 37, which may be of the rotary type, is provided with a central chamber 38 and a radial port 39 through which pressure fluid flows from the chamber 38 to a passage 40 in the back head and leading to a supply reservoir 41, also in the back head 36.

The valve mechanism 30 constructed in accordance with the practice of the invention comprises a valve chest 42 consisting of a pair of plates 43 and 44 and an annular member or ring 45 interposed between the plates. The plate .44, which constitutes the rearrnost part of the valve chest, serves as a seat for the ratchet ring 31 and the head 33 of the rifle bar, has a forwardly extending hollow stem 46 to serve as a bearing for the rifle bar 32 and also as a guide for a distributing valve 4'? reciprocable thereon for distributing the pressure fluid to the ends of the piston chamber 22.

The front end of the guide 46 preferably terminates in the same transverse plane as the corresponding end of the plate 43 and serves as an inner bounding surface for an annular passage 48 in the plate 43, and constituting a rear inlet passage through which pressure fluid flows into the rear end of the piston chamber 22 from a valve chamber 49 containing the valve 47. In the rear end of the valve chamber 49 is an annular space or chamber 50 which is defined by the extension 46 and the ring 45 and communicates with the front end of the piston chamber 22 through a front inlet passage 51.

Pressure fluid distributed by the valve 4'7 is conveyed from the supply reservoir 41 by a supply passage 52 located in the ratchet ring 31, the plate 44 and the ring 45. The passage 52 opens into an annular chamber 53 adjacent the periphery of the valve chamber 49 and communicating therewith through an annular groove 54 in the ring 45. V

The valve 47, which is in the form of a sleeve, carries at its rear end an external flange 55 of which the outer edge extends into the annular groove 54. The flange is of smaller diameter than the groove 54 to provide a restricted amiular space 10 around the flange 55 for the passage of pressure fluid over the edge of the flange 55 into the space 50 for supplying the front end of the piston chamber 22.

On the adjacent ends of the plate 43 and the ring 45 are raised portions which constitute seating surfaces 56 and 57 for the flange 55 and said raised portions may, as shown, be of smaller diameter than the flange so that outer annular portions of both sides of the flange 55 may be constantly exposed to pressure fluid to assist in throwing the valve when the pressure drops on one side or the other of the flange 55 at the instant the piston uncovers the exhaust port 24. The width of the grooves 53 and 54 and the distance which the flange 55 extends thereinto will, of course, vary with the weight of the valve but should in all cases be such that the influence of the drop in pressure in the passage 48 is not extended beyond the edge of the flange 55. Thus, when a drop in pressure occurs forwardly of the valve upon uncovering the exhaust port 24 there will remain an outer zone of pressure fluid of substantially line pressure in the groove 54 to maintain pressure of that value on the outer annular portion of the rear end of the flange 55. The opposite or front end of the valve 47 preferably extends into the annular passage 48 and is provided with a flange or shoulder 58 of smaller diameter than the flange 55 and also of smaller diameter than the passage 48 to provide a. restricted annular space 11 around the shoulder 58. The space 11 is of lesser capacity than the flow area between the flange 55 and the seat 56, so that the suction of the pressure fluid flowing through the passage 48 into the rear end of the piston chamber 22 will become effective as a factor for throwing the valve forwardly immediately after the exhaust port 24 is uncovered.

The portions of the valve 47 lying inside of the seating surfaces 56 and 57 constitute pressure areas 59 and 60 on the front and rear portions of the valve, respectively, and said pressure areas are intermittently subjected to compression from the piston chamber to assist in throwing the valve.

The operation of the device is as follows: With the valve 47 and the piston 23 in the positions illustrated in Figure 1 pressure fluid flows across the pressure area 59 through the rear inlet passage 48 into the rear end of the piston chamber 22 and drives the piston 28 forwardly on its working stroke. The valve 47 will be held in this rearward position by the pressure fluid acting against the front surface or surfaces of the valve until the piston uncovers the exhaust port 24 and causes an abrupt reduction in pressure forwardly of the valve.

The pressure fluid flowing over the edge of the shoulder 58, the compression created in the front end of the piston chamber acting against the pressure area 60 and the pressure fluid in the rear end of the groove 54 will then shift the valve 47 forwardly to the position illustrated in Fig ure 2, and wherein the valve flange 55 seats against the seating surface 56. Pressure fluid then flows around the edge of the flange .55 through the space 50 and the inlet passage 51 into the front end of the piston chamber 22 to return the piston 23 to its initial position.

During the rearward travel of the piston 23 the air compressed thereby in the rear end of the piston chamber acts against the front pressure area 59 and will tend to again shift the valve rearwardly. At the instant the piston 23 uncovers the exhaust port 24, and at which time there is an abrupt drop in pressure in the chamber 50, the pressure fluid flowing over the edge of the flange 55, together with the compression acting against the pressure area 59 and the pressure fluid acting against the outer annular portion of the front end of the flange 55, will shift the valve rearwardly against the seating surface 57, thus completing the cycle of operation.

In practice it has been found that a valve constructed and arranged in the manner described is particularly desirable for use in rock drills intended for work requiring a heavy blow. Owing to the relatively small diameter of the shoulder 58 and the consequent small area thereof exposed to the draught of the pressure fluid the pressure in the rear end of the cylinder must fall to a comparatively low value before the forces acting against the flange and the shoulder may become effective to throw the valve forwardly. This assures a full driving charge behind the piston which will, therefore, deliver a heavy blow against the working implement. On the other hand, when the piston is moving rearwardly and when it uncovers the exhaust port 24 the pressure fluid flowing over the edge of the comparatively larger flange 55 will cause the valve to be reversed against a counter pressure of comparatively high value, thus compensating for any slight loss of time incident to the reversal of the piston in the front end of the piston chamber and the drill will, therefore, com plete its cycle of operation in at least the same periodof time as the conventional type of lightstroke drill.

In the form of the invention illustrated in Figures 3 and 4 the valve is identical to that disclosed in Figures 1 and 2 but is reversed so that the flange 55 lies in the front end of the valve chamber and its edge is subjected to draught of the pressure fluid flowing to the rear end of the piston chamber. The valve chest housing the valve consists of a pair of plates 61 and 62 of which the plate 62 serves as a closure for the rear end of the piston chamber 22, and the plate 61, seated on the plate 62, serves as a support for the ratchet ring 31 and the head 33 of the rifle bar 32. The plates are provided with axial bores 68 for the accommodation of a guide member 64 which serves as a bearing for the rifle bar 32 and as a guide for the distributing valve 47 operative in a valve chamber 65. The flange 55 of the valve seats alternately upon seating surfaces 66 and 67 on annular raised portions of the plates 62 and 61, respectively, and is of slightly smaller diameter than an annular groove 68 in the plate 62, and into which it extends, to provide a restricted annular space 69 through which the pressure fluid flows to rear inlet passages 70 connecting the valve chamber 65 with the rear end of the piston chamber 22.

The shoulder 58, of the valve, extends into an annular chamber 71 in the plate 61 and is also of slightly smaller diameter than said chamber to form an annular space 12 around the shoulder so that the pressure fluid flowing through the space 12 will exert a suction on the shoulder to assist in actuating the valve rearwardly. A front inlet passage 72 leading from the chamber 71 conveys pressure fluid to the front end of the piston chamber 22 for driving the piston 23 rearwardly.

The operation of this form of the invention and the manner in which the forces are "applied for actuating the valve are substantially similar to the operation described in connection "with the form of valve previously described, with the. exception, however, that the pressure fluid passes over the large flange into the rear end'of-the piston chamber and over the shoulder 58 to the front end of the piston chamber.

Owing to this arrangement of the valve an immediate large supply of pressure fluid may pass through the relatively large space 69 and be introduced behind the piston to drive it on its working stroke at the instant the valve is lifted to uncover the inlet passage '70. By reason of the fact that a greater area, such as that provided by the flange, will be subjected to the force of suction of the pressure fluid the valve will be thrown quickly forward at the instant when the piston uncovers the exhaust port 24, thus preventing the direct flow of pressure fluid from the valve chamber through the piston chamber and the exhaust port to the atmosphere. Owing to the further fact that a relatively small area of the shoulder 58 is subjected to the drag of the pressure fluid for reversing the valve a comparatively low pressure must exist in the front end or" the piston chamber before the valve will be unseated and moved rearwardly at a slightly later period during the rearward stroke of the piston which will then complete its nominal stroke, rearwardly, before the valve is again reversed instead of short-stroking.

I claim:

1. In a fluid actuated rock drill, the combination of a cylinder and a piston therein, avalve chest having a valve chamber and front and rear inlet passages for supplying pressure fluid to the ends of the cylinder, a valve in the valve chamber, a flange on the valve controlling the flow of pressure fluid to the inlet passages and having its edge subjected to the suction of the pressure fluid flowing to one inlet passage for throwing the valve in one direction, and a shoulder on the valve of smaller diameter than the flange and having its edge subjected to the suction of the pressure fluid flowing through the other inlet passage for throwing the valve in an opposite direction.

2. In a fluid actuated rock drill, the combination of a cylinder and a piston therein, a valve chest having a valve chamber and front and rear inlet passages for supplying pressure fluid to the ends of the cylinder, a valve in the valve chamber, a flange on the valve controlling the flow of pressure fluid to the inlet passages and having its edge subjected to the suction of the pressure fluid flowing over the flange to one inlet passage for throwing the valve in one direction, and a shoulder on the valve lying in the other inlet passages and having its edge subjected to the pressure fluid flowing through the last mentioned passage for throwing the valve in an opposite direction.

3. In a fluid actuated rock drill, the combination of a cylinder and a piston therein, a valve chest having a valve chamber and front and rear inlet passages for supplying pressure fluid to the ends of the cylinder, a valve in the valve chamher, a flange on the valve controlling the flow of pressure fluid to the inlet passages and having its edge subjected to the suction of the pressure fluid flowing over the flange to one inlet passage for throwing the valve in one direction, a shoulder on the valve lying in the other inlet passage and having its edge subjected to the pressure fluid flowing through the last mentioned passage for throwing the valve in an opposite direction, and opposed pressure areas on the valve subjectedintermittentlyto compression from the cylinder to assist .in throwing the valve.

4."In a fluid actuated rock drill, the combination of acylinder and a piston therein, a valve chest having a valve chamber and front and rear inlet passages for supplying pressure fluid to the ends of the cylinder, a valve in the valve chamber and having a bore, means in the bore to guide the valve, a flange on the valve controlling the distribution of pressure fluid to the inlet passages and having its edge subjected to pressure fluid flowing to one inlet passage for throwing the valve in one direction, opposed areas on the flange constantly exposed to pressure fluid to assist in throwing the valve, a shoulder on the valve over which the pressure fluid flows to one end of the cylinder and having its edge subjected to the suction of the pressure fluid for throwing the valve in an opposite direction, and opposed pressure areas on the valve subjected intermittently to compression from the cylinder to assist in throwing the valve.

5. In a fluid actuated rock drill, the combination of a cylinder and a piston therein, a valve chest having a valve chamber and front and rear inlet passages for supplying pressure fluid to the ends of the cylinder, a guide member in the valve chest, a valve in the valve chamber guided by the guide member, a flange on the valve controlling the inlet passages and being actuated in one direction by the pressure fluid flowing over the edge of the flange to the front end of the cylinder, a shoulder on the valve subjected to the suction of the pressure fluid flowing thereover to the rear end of the cylinder for throwing the valve in an opposite direction, and opposed pressure areas on the valve subjected to compression from the cylinder to assist in throwing the valve.

6. In a fluid actuated rock drill, the combination of a cylinder and piston therein, a valve chest having a valve chamber and front and rear inlet passages for supplying pressure fluid to the ends of the cylinder, a guide member in the valve chest, a valve in the valve chamber guided by the guide member, a flange on the valve chest controlling the inlet passages and being actuated in one direction by the pressure fluid flowing thereover to the front inlet passage, a shoulder on the valve of smaller diameter than the flange and being subjected to the suction of the pressure fluid flowing through the rear inlet passage, and opposed pressure areas on the valve subjected to compression from the cylinder to assist in throwing the valve.

'7. In a fluid actuated rock drill, the combination of a cylinder and a piston therein, a valve chest having a valve chamber and front and rear inlet passages for supplying pressure fluid to the ends of the cylinder, a guide member, a valve in the valve chamber guided by the guide member, a flange on the valve controlling the flow of pressure fluid to the inlet passages and being actuated in one direction by the pressure fluid flowing thereover to the rear inlet passage, a shoulder on the valve of smaller diameter than the flange and being subjected to the suction of the pressure fluid flowing to the front inlet passage, and opposed pressure areas on the valve subjected to compression from the cylinder to assist in throwing the valve.

8. In a fluid actuated rock drill, the combinathe valve of smaller diameter than the flange and having its edge subjected to the suction of the pressure fluid flowing through the other inlet passage for throwing the valve in an opposite direc tion, and opposed areas on the flange constantly exposed to pressure fluid to assist in throwing the valve.

GEORGE W. HULSHIZER. 

